Snapshot of Seismic Waves Traveling Across Virginia

The M5.8 earthquake centered in eastern Virginia on Tuesday was among the largest recorded* in the eastern United States and the second largest recorded in Virginia. I’m sure you’ve read numerous articles summarizing the basic geology of this seismic event. But if you’re looking for some more detail, you need to read Callan Bentley’s post (from the blog Mountain Beltway), which includes a very lively Q&A and discussion in the comment thread. Callan is a talented educator of Earth science and it shows in this post.

The images above display data recorded by my institution’s seismological outfit, the Virginia Tech Seismological Observatory, which has several seismometers deployed around the state. The wiggle trace measures the vertical movement the seismometer experiences from the seismic waves. This is a nice, simple illustration showing how the stations further away from the epicenter (from top to bottom) record the shaking at later times. If you’re feeling especially seismo-nerdy you could calculate an estimate of how fast these seismic waves traveled. See this page from VTSO for more information.

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* Reliable measurements/estimations of magnitude go back a couple hundred years; the occurrence of larger earthquakes further back in time is uncertain.